Friday, 25 February 2022
Wire rope slings continue to be important lifting tools. Nobles’ own Nobleflex wire rope slings provide a solution which works well and makes the slings last longer. Nobleflex has outstanding flexibility and kink resistance that help with issues of excessive wear and tear wherever basic wire rope slings are used.
Wire rope slings are essential lifting tools. Their resilience under arduous conditions and the enormous range of available sizes, make them a staple of lifting operations worldwide.
As a sling material, wire rope brings a number of benefits:
• A galvanised surface finish to resist corrosion
• An all-metal construction, invulnerable to sunlight & ultraviolet radiation
• A compact sling body, able to be passed through tight spaces
• A flexible load bearing material, which can be run over sheaves and pulled by winches
• Temperature resistance ranging from good to excellent
• An inspectable material, made up of 100s of load bearing wires which tend to progressively de-grade with wear and abuse, limiting the potential for sudden failure
• Good resistance to cutting, abrasion & wear
• Good resistance to shock and vibration.
All told, wire rope slings provide excellent assurance against in-service failure, which is why they are frequently the go-to solution wherever there are concerns about abusive conditions possibly diminishing user safety.
As a flexible and resilient sling choice, wire rope maintains a clear advantage against moderate temperature exposure. Even when temperatures are comfortably within limits, synthetics deserve extra care to avoid sling slip under load and the localised heat from friction that may result.
Where temperature or friction from sling slippage are risks – selecting an all-metal sling type improves confidence.
Ordinary wire rope slings have their downside. They simply aren’t as easy to pack into storage as synthetics, or even chain. Their lack of flexibility when being handled into position can make them ‘lively’ and create additional effort. They also can be prone to suffering permanent kinks in use, particularly if treated poorly.
Fortunately, there is a better version of this product, and it’s one that has been a popular solution for decades – Nobles’ very own Nobleflex slings.
Nobles Nobleflex Wire Rope
Improve on sling rope
Like all sling types, wire rope for slings has application properties that are fundamentally related to its size (diameter). These govern the relative size of termination fittings, the rules for contact with the corners of payloads and the general ease of handling and user friendliness of the material. What the Nobleflex product does, is combine the reassuring virtues of wire rope with its fundamental nature – the combination of many wires to form a whole – to make a sling which is simply better. By using what are in-effect a collection of smaller ropes.
Easy to flex
When picking a Nobleflex sling off a sling rack, the improvement is immediately apparent. The sling does what the user wants it to without any effort to fight it into place.
A Nobleflex sling end flexing easily under its own weight
Resistance to abuse
In truth, no sling type is immune from sharp corner abuse. Specifying wire rope as opposed to other sling types is something that many sites do, to limit their exposure to acute sharp-edge-to-sling concerns.
What is striking about Nobleflex however is that in the face of such risks – it simply lasts longer.
After a single lift in abusive conditions the regular wire rope sling (bottom) already has concerning kinks, in contrast the Nobleflex sling (top) survives to pass inspection.
Contact Radius for Square Loads
Wire rope slings in basket or choke configurations operate with two ratings depending upon whether the payload that the sling is wrapped around is ‘square’ or ‘round’. Circular payloads have no requirement to de-rate the sling, but there are limits – with the acute angle rule of AS1666.2 coming into force the round payload must have a radius of at least 5 times the diameter of the sling to be considered ‘round’.
Limitations of wire rope slings per AS1666.2-2009 8 (b) (i)
Where a load is considered ‘square’ the WLL is halved for basket hitches and reduced by a further third for choke hitches. Under these conditions the corner bend radius must be at least the diameter of the rope.
Figure 1, can sometimes seem confusing, because the square load rule is shown with an obtuse angle in the rope path. This makes more sense following the guidance to protect the sling from sharp corners as in figure 2.
Protective packing can offer a combination of radiused bends and obtuse angle sling paths.
Other practical considerations can be deduced from this set of rules, for example – if a payload is triangular, then the corner protection for slings must offer a radius of 5 times diameter. Alternatively, the payload must be packed out with protection to ensure no bends are less than 90 degrees.
Corner radius rules must be emphasised for all sling types, so it is important when procuring lifting tackle to ensure that the end user is properly equipped to obey them.
This means that sling racks should be equipped with a variety of sling types that are suited to the operating environment, that the right training is provided to users, and that a selection of edge protection materials are stored nearby, ready to be available when needed.
Nobleflex slings can help
Wire rope slings which are formed from multiple ropes reduce the effective diameter that is in contact with edges by offering proportionally smaller rope diameters to the job. Such slings can come in a variety of forms: 2- part slings, 3- and 5- part slings, braided slings, and cable-laid slings. Each of these have their own pros & cons. The simplest kind are 2- part slings, sometimes referred to as ferrule secured grommets.
Ferrule Secured Grommet
These aren’t always convenient, but they are easily made and give 50% more strength than the parent rope and in-turn, for a given working load limit (WLL) the rope itself can be about 18% smaller and more tolerant of corners.
Nobleflex falls into the cable-laid category and in the sizes 11 to 22mm is stocked in a highly stable machine-made form which has the advantage of behaving for all intents like a regular rope when it needs to, whilst retaining its extra benefits.
Being cable laid, an additional de-rate category is available for square loads with corners below the 1 times diameter minimum and with a minimum of ½ times diameter. This is derived from the international standard for cable laid slings IMCA M179 and equates to an additional 42% reduction in capacity for square loads at a ½ diameter minimum radius.
Nobleflex in Accordance with AS1666
Nobleflex wire rope slings are available in any required length and configuration for your project. All slings are manufactured, labelled and proof load tested as required by Australian Standard AS1666. You can confidently do yourself and fellow sling users a favour by adding Nobleflex slings to your sling rack today.
How Can We Help?
Nobles offer all types of sling types to suit the full diversity of application requirements. We are on hand with all the information you need to know, speak to our customer service team by calling 1300 711 559 or email us at firstname.lastname@example.org to get professional advice and to discuss your slings and rigging requirements.